Rotor-Racing I-Laps sensor bar

thingiverse

UPDATE July 4, 2017: Added STLs for 40mm pipe Rotor-Racing has been using the I-Laps infra-red timing system since we started running drone races. The system uses 3 or more IR sensors mounted on or near the start/finish gate to detect the unique ID transmitted from an IR transponder on each drone. This sensor bar creates a sensor array with cheap, readily available PVC tubing that compensates for drones crossing the line at high bank angles. A minimum of 3 sensors is recommended, but we use 5 for standard BFPVRA/FAI gates (3 in the vertical section and 1 each in the 45-degree sections). The main bar is constructed from ~3m of tubing with a 135deg elbow for the bend at the top and a 135deg tee for the kick at the bottom. We use a standard weighted flag stand to hold it up, but a ground spike works equally well. The design includes spacers to pad out the flag stand pin to fit the vertical tubing. The aperture template allows us to line up and mark out the sensor recess before cutting it out, ensuring the smallest hole possible that lets the sensor be inserted while maximizing rigidity of the pole and resilience against drone collisions. The wedges are hot-clued to the back of the sensor bar and provide a flat surface to mount the sensors (we use velcro for this), keeping them well protected inside the tube without compromising their field of view. This whole model is parametrically designed in OpenSCAD, so I can produce parts for any size tubing by tweaking a few numbers. I've uploaded STLs for 32mm and 36mm tubing, but if you need other sizes, just leave a comment with inner/outer dimensions and I'll create another variation.